Two types of projection display systems are digital light processor (DLP) systems, and liquid crystal display (LCD) systems. It is desirable in some projection applications to provide a high lumen level output, but it is very costly to provide such output levels in existing DLP and LCD projection systems. Three choices exist for applications where high lumen levels are desired: (1) high-output projectors; (2) tiled, low-output projectors; and (3) superimposed, low-output projectors.
When information requirements are modest, a single high-output projector is typically employed. This approach dominates digital cinema today, and the images typically have a nice appearance. High-output projectors have the lowest lumen value (i.e., lumens per dollar). The lumen value of high output projectors is less than half of that found in low-end projectors. If the high output projector fails, the screen goes black. Also, parts and service are available for high output projectors only via a specialized niche market.
Tiled projection can deliver very high resolution, but it is difficult to hide the seams separating tiles, and output is often reduced to produce uniform tiles. Tiled projection can deliver the most pixels of information. For applications where large pixel counts are desired, such as command and control, tiled projection is a common choice. Registration, color, and brightness must be carefully controlled in tiled projection. Matching color and brightness is accomplished by attenuating output, which costs lumens. If a single projector fails in a tiled projection system, the composite image is ruined.
Superimposed projection provides excellent fault tolerance and full brightness utilization, but resolution is typically compromised. Algorithms that seek to enhance resolution by offsetting multiple projection elements have been previously proposed. These methods assume simple shift offsets between projectors, use frequency domain analyses, and rely on heuristic methods to compute component sub-frames. The proposed systems do not generate optimal sub-frames in real-time, and do not take into account arbitrary relative geometric distortion between the component projectors, and do not project single-color sub-frames.
Existing projection systems do not provide a cost effective solution for high lumen level (e.g., greater than about 10,000 lumens) applications.
In addition, in the field of use of digital cinema, current projection vendors are attempting to sell very highly priced projection systems with an uncertain technical future to theaters that typically can neither afford the investment nor afford the technical risk. From the point of view of exhibitors (theater owners), digital cinema is a very expensive investment with a high degree of uncertainty. The cost of dedicated projection equipment and infrastructure is very high. New revenue streams from showing alternative digital content such as advertising and event display are in the early stages of evolution. Even if a theater did pay for the up-front equipment cost, the large payback duration puts the theater at risk of technology obsolescence for example, from new projection technologies around the corner, such as laser projection. Further, existing systems are not configured to allow exhibitors to allocate and reconfigure projection resources dynamically.